An adhesive is a substance capable of holding materials (e.g., adherends or substrates) together by surface attachment. Pressure sensitive adhesives (PSAs) generally are adhesive materials which bond to adherends when a required pressure is applied to effect an adhesion to the adherends. PSAs can be permanent or removable. Removable PSAs have been widely used in re-positionable applications, such as Post-it® notes. Pressure sensitive adhesives are generally based on a polymer, a tackifier and an oil. Some common PSAs are based on polymers such as natural rubbers, synthetic rubbers (e.g., styrene-butadiene rubber and styrene-isoprene-styrene copolymer), polyacrylates, polymethacrylates, and poly-alpha-olefins.
Hot-melt adhesives at ambient temperature are generally solid materials that can be heated to a melt to hold adherends or substrates together upon cooling and solidifying. In some applications, the bonded substrates can be detached by remelting the hot melt adhesive if the substrates can withstand the heat. The hot melt adhesives are generally used in paper products, packaging materials, laminated wood panels, kitchen countertops, vehicles, tapes, labels, and a variety of disposable goods such as disposable diapers, hospital pads, feminine sanitary napkins, and surgical drapes. Generally, these hot melt adhesives are based on a polymer, tackifier, and a wax. Some common hot melt adhesives are based on semi-crystalline polymers such as ethylene homopolymers, ethylene copolymers and styrene block copolymers (e.g., styrene-isoprene-styrene copolymer or styrene-butadiene-styrene copolymer). One desirable property of hot melt adhesives is the absence of a liquid carrier, thereby eliminating a potential costly and hazardous process associated with solvent removal.
Polymers derived from terpenes or isoprenoid compounds are useful polymeric materials. For example, polyisoprene, polypinene and polylimonene have been used in various applications such as in the manufacture of paper coatings, rubber compounds, and other industrial products. However, adhesive compositions comprising polymers derived from terpenes or isoprenoid compounds are rare, even rarer are polymers derived from isoprenoid compounds having at least 15 carbon atoms.
Despite the availability of a variety of hot melt adhesives and pressure sensitive adhesives, there are still needs for new adhesive compositions having unique adhesive properties to meet new requirements. Further, there is a need for environmentally friendly or renewable polymers, for instance, polymers derived from isoprenoid compounds that can be obtained from natural sources.